The present invention relates generally to prosthetics, and more specifically to dental implants, and, even more specifically to a dental implant, support post, and a screw having conical head, and, further more specifically to a support post having a hexagonal groove at the bottom and a hollow countersink to hold the aforesaid screw, and, an implant having a conical passage with the protruding hexagonal structure to partially accommodate the mentioned screw.
A dental implant is a device which is biocompatible and bio functional and is placed on or within the bone associated with the oral cavity to provide support for fixed or removable prosthetic teeth by means of screws.
frequently, the screws used in connection with the prosthesis may break on the inside of an implant, causing serious problems by damaging both the fixture and/or the prosthesis. A screw fracture is usually caused by abnormal stresses produced by the prosthesis. Another problem associated with dental implants is the loosening of screws that hold the implants in position.
The loosening action depends on stress forces typically caused by masticating forces (refer FIG. 1). However, depending on the frequency and/or the intensity of these forces, it is very likely to lose friction between the male and female threads that maintain the integrity of a coupling. What follows is imperceptible movement and micro-oscillations that subsequently can cause significant movement in the threading of the screw. This concept is common to virtually all fixation screws.
Considering a simple screw mechanism, on connecting the male and female counterparts without threading them completely, a small vertical movement can be noted. This is due to slight differences between the two threads and the space between them, called “tolerance” (refer FIG. 2).
Although engaging the thread completely causes the movement to cease because it enters a perfect engagement and fit (refer FIG. 3), mastication increases the deformation of the threads and causes the male part to rotate and unscrew over a period of time. This results in loosing of joint, and possibly a fracture.
U.S. Patent publication number U.S. Pat. No. 6,152,737 discusses a support post for use with a dental implant for supporting prosthesis. The problem with such post implants is that the screw, which connects the support post to the dental implant, is held at the shoulder region of the support post and hence the surface area in contact between the screw and the support post is substantially less resulting in a limited friction between the screw and the support post which intern results into loosening of the screw because of masticating forces. Further in this invention the screw head does not have any contact with the implant and therefore when a pressure is exerted on screw head, pressure is experienced by the thread and the bore area, which causes damage of the screw threads that may lead to fracture of screw and consequently the fracture of the implant itself. The constructional features of the invention are described in para [0031].
In another analogous art, U.S. Patent publication number U.S. Pat. No. 6,848,907 describes a screw for dental implant. This invention has similar limitations as discussed in the above-mentioned prior art.
In mentioned prior arts the torque and pressure exerted on the screw is unevenly distributed which causes breaking of the screw and damaging the implant; thus requiring surgical intervention. Therefore, the present scenario is punctuated by an emerging need for a dental implant that distributes the torque and the pressure evenly on the screw.
In view of the foregoing disadvantages inherent in the above-mentioned techniques, a general object of the present invention is to obviate above and other drawbacks associated with the prior art; to provide a system for an implant which can evenly bear the pressure exerted; to provide an improved assembly; to provide a screw with conical head which bears all the pressure thus preventing from the implant from fixture.
Other objects of the present invention are to provide a support post with an improved design which houses the screw conical head of the screw providing better holding and reducing the chances of under threading; to provide an improved implant with a conical passage to partially hold the conical head of the screw; and to hold the support post and implant firmly to prevent vertical circular motion of the support post over the implant. These and other objects of the present invention will become better understood with reference to the appended Summary, Description and Claims.